1. (adj.) A modern synonym for words such as "cool," "ill," "tight," or "dope." Used to describe a noun that is of a particularly excellent quality. The slang use of this term is slowly but steadily increasing in popularity.

this word was obviously a short form of "legitimate" but it no longer holds the same meaning as legitimate, since it has become very popular to use the word legit to mean something "cool", which really has nothing to do with the word legitimate and therefore we should stop saying it.